i=0
while i<10:
    print('hello world')
    i=i+1

i=0
while i<10:
    print('★',end='')
    i=i+1
i=0
print('')
while i<5:
    print('★☆',end='')
    i=i+1
print('')
i=1
sj=0
so=0
while i<101:
    if i%2==0:
        so=so+i

    else:
        sj=sj+i
    i=i+1
print(sj)
print(so)

i=1
sj=0
so=0
while i<101:
    if i%2==0:
        so=so+i
    else:
        sj=sj+i
    i=i+1
print(f'奇数和为{sj},偶数和为{so}')

cj=int(input('请输入成绩:'))
while 0<=cj<=100:

    if cj>=90:
        print('A')
    elif cj>=80:
        print('B')
    elif cj>=70:
        print('C')
    elif cj>=60:
        print('D')
    elif cj>=0:
        print('E')
    cj=int(input('请输入成绩:'))

j=1
n=1
so=0
while n<5001:
    so=so+j*1/n
    n=n+2
    j=j*-1
print(4*so)

i=0
j=0
while i<5:
    while j<10:
        print('★', end='')
        j=j+1
    j=0
    print('')
    while j < 10:
        print('☆', end='')
        j = j + 1
    j = 0
    print('')
    i=i+1
print('')
while j<10:
    i = 0
    while i < 5:
        print('★☆', end='')
        i = i + 1
    print('')
    j = j + 1
